A conventional torque wrench of this type has a tightening unit such as a ratchet wrench, a housing with a separable two-piece structure comprising a front side cover part and a back side grip part, a strain body that is provided inside the housing and is coupled with the replaceable tightening unit, distortion sensors that detect distortion amount of the strain body, a microprocessor chip having functions including computation of a tightening torque based on the detection result of the distortion sensors, and an output unit that outputs the tightening torque, etc. (See Patent Literature 1).
Patent Literature 1: JP 2006-289535 A